1. Field of the Invention
The present invention relates to a head suspension for a disk drive incorporated in an information processing apparatus such as a personal computer.
2. Description of the Related Art
A hard disk drive (HDD) records and reproduces information to and from rotating magnetic or magneto-optical disks. The HDD has a carriage that is turned around a spindle by a positioning motor.
An example of the carriage is disclosed in U.S. Pat. No. 4,167,765. The carriage of this disclosure includes carriage arms, a head suspension attached to a front end of each carriage arm, a head attached to the head suspension, and a slider attached to the head. When the disks are rotated at high speed, the sliders slightly float from the disks, and air bearings are formed between the disks and the sliders.
The head suspension includes a load beam made of a precision thin plate spring, a flexure made of a very thin plate spring fixed to a front part of the load beam by, for example, laser welding, and a plate fixed to a base of the load beam by, for example, laser welding. The plate is fixed to a head suspension fitting face of the carriage arm.
Recent hard disk drives employ high-density disks and drive the disks at high speed. For such high-density disks, the head suspensions must have excellent vibration characteristics to correctly position the heads on recording faces of the disks, as well as characteristics to avoid the influence of air disturbance caused by the disks rotating at high speed. To satisfy such and other requirements, the head suspensions are frequently subjected to intricate processes.
The high-density disks require head suspensions having high rigidity and low spring constants. To meet the requirement, the present inventor proposed in Japanese Patent Laid Open Publication No. 2001-155458 a head suspension 101 of FIG. 17, which is different from a conventional head suspension that employs a load beam composed of an integrated rigid part and resilient part.
The head suspension 101 of FIG. 17 has a plate 103, a load beam 105, and a flexure 107.
The plate 103 is attached to a carriage arm of a carriage. The carriage drives the head suspension 101 around a spindle.
The load beam 105 applies load on a slider 108 arranged at a front end of the load beam 105. The load beam 105 consists of a rigid part 109 and a resilient part 111. The resilient part 111 is made of a resilient material 113 that is independent of the rigid part 109.
The resilient material 113 is a rectangular plate and has an opening 115 to define the resilient part 111. A first side 113a of the resilient material 113 is laid on an end 109a of the rigid part 109 and is fixed thereto by, for example, laser welding or bonding. A second side 113b of the resilient material 113 is laid on an end 103a of the plate 103 and is fixed thereto by, for example, laser welding or bonding.
The flexure 107 is attached to the rigid part 109 of the load beam 105 by, for example, laser welding and is extended over the resilient material 113 toward the plate 103. The flexure 107 consists of a metal base 117 made of, for example, a resilient thin stainless steel rolled plate, an electric insulating layer formed on the metal base 117, and a conductive path 119 formed in the insulating layer. An end of the conductive path 119 is electrically connected to a terminal of the head 121, and the other end thereof is electrically connected to a terminal 123 for external connection.
In the head suspension 101, the load beam 105 consists of the rigid part 109 and resilient material 113 that are independent of each other. Namely, the rigid part 109 and resilient material 113 may be made of proper materials of their own and may have proper thicknesses of their own, to easily and simultaneously realize required properties such as high rigidity for the rigid part 109 and a low spring constant for the resilient part 111. The resilient part 111 may be made of a precision rolled plate, to provide a stable low spring constant.
The separate rigid part 109 and resilient material 113, however, form an overlapping part 125 between them. Where the flexure 107 rides on the overlapping part 125, contact between the flexure 107 and the load beam 105 deteriorates. This causes a problem that air enters into gaps between the flexure 107 and the rigid part 109, resilient material 113, and plate 103 around the resilient material 113. As a result, when disks are rotated at high speed, air disturbance will flutter the flexure 107 and make the flexure 107 touch the disks to damage the disks and flexure 107.
If the rigid part 109 and resilient material 113 are made integral with each other, there will be no overlapping part 125 on which the flexure 107 rides. Even with such an integrated structure, the flexure 107 must be extended from the rigid part 109 toward the plate 103, and therefore, the flexure 107 will flutter due to air disturbance or asynchronism between the movements of the flexure 107 and resilient part 111.